Sheetsxsheet i



DIAMOND DRILL BIT FOR ROTARY WELL. DRILLING Original Filed July 26, 1951 2 SHEETS-SHEET l INVENTOR ATTORNEYS March 10, 1953 J. A. zUBLlN Re. 23,632

J A ZUBLIN March l0, 1953 DIAMOND DRILL BIT FOR ROTARY WELL DRILLING Original Filed July 26, 1953 2 SHEETS SHEET 2 h/Mh 64am, @m110119- INVENTOR ATTORNEYS 0 D. o C D 0 U n O0 Reiseued Mer. 10, 1953 l Re. 23,632

DIAMOND DRILL BIT FR ROTARY WELL DRILLING John A. Zublin, Los Angeles, Calif.

Original No. 2,614,809, dated October 21, 1952, Se-

rial No. 238,697, July 26, 1951. Application for reissue November 20, 1952, Serial No. 321,749

(Cl. 255-61) Matter enclosed in heavy brackets appears in the original patent but forms no part of this 6 Claims.

reissue speciiication;

This invention relates to a novel diamond drill bit more particularly adapted for drilling in extremely hard formations. The bit is especially applicableto the'drilling of relatively small diameter bores deviatlng from existing Well bores.

Diamond rotary core bits have been in use for a number of years which are effective to cut a core having a diameter equal to the interior diameter of a hollow core bit. Commercially, diamond drill bits have |been largely limited to core drilling because Athe diamond cutting elements do not have great resistance to shock or impact loads. The drilling of -open well bores with diamond drill bits, that is, bits studded with diamond cutting elements, has presented problems which have not. to applicants knowledge, been heretofore satisfactorily solved. The cutting of a. clean bore, of course, necessitates removal of the formation at the exact center of the well bore as well as at the periphery thereof. A diamond cutting element positioned .at the center of the well bore. of course, merely rotates about its own axis and will not long effectively perform any satisfactory cutting operation and, furthermore, will soon shatter because of its inability to stand the strain.

It is among the purposes and objects of the present invention to provide a diamond drill bit which is effective in drilling an open bore and which will have long life in operation in the drilling of hard formations.

More specifically, it is an object of the invention to provide a diamond drill bit effective to remove the outer portion, i. e., peripheral portion, of the formation of the bottom of the bore being drilled while the inner or central portion is allowed to protrude into the bit in the form of a cone, the apex of which coincides with tho axis of rotation of the bit.

Through the provision of a diamond blt having a conical recess the exposed wall of which is studded with diamonds, the cone of the formation. which extends into the conical recess of the bit is continuously cut away as the drilling proceeds and the diamond cutting elements near the apex of the conical recess of the bit are subjected to relatively little strain since, at that point, the formation being cut is of exceedingly small diameter and easily .sheared or vbroken oli.

It is a further and more specic object of the invention to provide the conically recessed diamond studded bit with channels for the circulating fluid which will be effective to free the cutting face of the bit from unwanted detritus.

It is a further and more specic object of the invention to provide a diamond cutting bit havmatter printed in italics indicates the additions made by reissue.

ing a central conical recess which communicates With a channel for receiving cut-away portions of the formation.

It is a further and more specific objectof the invention to provide a diamond drill bit having a conical recess in the cutting face thereof which will be effective under the drilling weight applied to the bit to shear and break off the central portion of the formation being removed by thebit.

Further and more specific objects of the invention will become apparent as the description proceeds, which will be given by reference to the accompanying drawings, wherein Figure 1 is a side elevational view of the diamond drill bit conforming to the present invention.

Figure 2 is a bottom plan view of the bit Ashown in Figure 1.

Figure 3 is a cross-sectional view along the line 3 3 of Figure 2.

Figure 4 is a fragmentary view similar to Figure 3 but disclosing the bit as it appears in action in the drilling of a well bore.

Figure 5 is a cross-sectional view of a modied form of the invention.

Figure 6 is a cross-sectional view through the complete bit of the modification shown in Figure 5 taken in the direction of the arrows on thc plane of the line 6-6 of Figure 5, and

Figure 7 is a detailed view of the removable element of a modication of Figure 5.

Referring to Figure 1, the bit body Ill has a threaded shank il by which it is adapted to be secured to the lower end of a suitable drill string section for rotation therewith` The bit body I0 and shank Il have an open channel I2 extending therethrough. The channel l2 is circular at its upper portion but is offset as indicated at i3 and takes the form of a flared semicircular chamber I4 which it will be observed is disposed entirely to one side of a plane perpendicular to Figure 3 extending through the axis A-A of the bit. The blt body Ill has a conical recess defined by the wall i5 to which wall a diamond cuttingr element carrying matrix I8 is suitably adhered so thatfin eiect, the -bitbody I0 and matrix I6 constitute a unitary structure. The matrix I6 covers all oi' the exposed surface of the conical recess in the bit body I0 and projects upwardly about the annular, marginal, lower end thereof as indicated at Il. The matrix i6 has cut in its exposed face a plurality of grooves lll, I9 and 2U which extend from the semicircular chamber il to the periphery of the bit and are cut where they communicate with vertical channels 2|, 22

and 23 respectively. The grooves Il-2 and channels 2I-23 provide free flow passageways for the circulating iluid employed in the drilling operation which is forced downwardly through the channel I2 in shank II thence through the offset portion I3 of the channel into the semicircular chamber I4 thence through the respective grooves I8-20 and then upwardly through the channels 2I--23. The lands or spaces between the grooves I8, I9 and 20 and their channel extensions 2|, 22 and 23, which lands are designated 24, 25 and 2l, carry heterogeneously mounted throughout their exposed areas diamond cutting elements 21. y

In operation the entire bit is, of course, rotated by the rotary drill string which extends to the surface of the well. By reference to Figure 4 it will be observed that the matrix IB embracing its annular upturned portion II provides an annular formation cutting face 28 which acts to cut a groove in the formation extending around the circumference of the bore. As the annular cutting face 28 penetrates the formation the upwardly extending lands 24, 25 and 26 carrying the diamond cutting elements 21 cut away what would otherwise be a circular core until it takes the fom of a cone designated 29 having the apex D in the axis of rotation A-A of the bit. The bit is, of course, impelled downwardly by the pressure P through imposition of weight on bit at the surface of the well. The semicircular opening I 4 terminates along the line F--F'. I-t will thus be apparent that that portion of the cone 29 which lies above the plane of the line F-F' and to the left of a plane perpendicular to Figure 4 passing through the axis A-A of the bit will be fully exposed in the semicircular opening I4. Only one half of the conical surface of the bit above the plane of the line F-F' is therefore available to carry diamond cutting elements 21. Under the pressure P representing the weight on bit the cone 29 gradually moves up into the conical recess of the bitl the lower part being cut away at the cutting face 2B and by the diamond cutting elements mounted in the lands 24, 2! and 2i. The f upper part of the cone 29, of course, has materially less surface and there are materially less diamond cutting elements acting on it. Thus, at the apex D of 'the cone 29 and for a distance somewhat therebelow, the cone will not be cut away as cated PI in Figure '4. The greater the tendency of the cone to bulge out near the apex, the greater' will be vthe pressure PI and this pressure is, of course,` always directly opposite the semicircular opening I4 and is available to shear and break oi the point of the cone above the plane passing through line F-F'. The harder the formation, the nearer the apex D the cone will be sheared or broken away. In softer formations it may well break away near the line F-F. The chamber I4 is of suillcient size to hold a considerable volume of pieces of formation broken away and sheared away from the cone. These are carried down through the grooves III, I9 and 2l, are further reduced in size and ultimately carried by the circulating fluid upwardly through the channels 2I, 22 and 23 and removed from the bottom of the well bore.

If the action of the bit slows down, indicating the chamber I4 may have become lled with broken cone pieces. the pump pressure on the cir- Cil culating uld will rise, indicating to the driller at the surface of the well the circumstance that the chamber I4 has become filled or clogged. The driller can then raise the bit for a foot or so from the bottom of the well and the circulating fluid will free the channel I2 and chamber I4 of all the pieces which have collected therein. These will fall into the annular circular groove around the cone and when the bit is again lowered they will be pulvergized and removed.

From the foregoing it will be appreciated that the diamond drill bit of the present invention is not dependent to any great extent upon effective cutting of the diamond cutting elements at the point of dead center of the bit. Indeed, the bit will be effective after the diamond cutting elements near the apex D and conical recess of the bit are substantially worn out.

In Figures 5, 6 and 7 there is shown a modified form of the invention in which the bit body 3l) is recessed at 3| to receive a specially formed plug 32 more particularly shown in Figure 7. The plug 32 seats against the annular shoulder 33 in the recess 3| at its upper end and is held in position in the bit body 30 by the screws 34 and 35. The plug 32 has a semicircular cut-out portion 36 to provide a semicircular chamber quite comparable to chamber I4 of the modification of Figures l-4. The semicircular chamber 3B communicates with the channel 31 in the shank 33. The diamond cutting element supporting matrix 39 is provided with a series of cut-out grooves 40 and vertical extending channels 4I. The plug 32 is so positioned in the recess 3l that three of the grooves 4I) open into the semicircular chamber 36 since three of these grooves are positioned to one side of the vertical plane passing through the axis of rotation of the bit (see Figure 6) The lands between the grooves 49 carry heterogeneously mounted diamond cutting elements comparable to the diamond cutting elements 21 in the modiilcation of Figures 1 to 4, and that portion of the plug 32 below the point 42 has a frusta-conical surface 43 which provides an extension of the conical cutting face directly opposed to the semicircular chamber 3B. The operation of the modified form of invention as disclosed in Figures 5-7 is the same as the preferred embodiment illustrated in Figures 1-4 and may be resorted to to facilitate ease of manufacture. In all forms of the invention the action of the bit results in the production of a cone or formation extending into the conical recess of the bit, the apex of which is sheared and broken away by the action of a component of pressure applied to the bit in the rotary drilling operation.

Having thus described my invention, what I claim is:

l. A diamond drill bit for drilling in hard formations, comprising a bit body. a channel extending downwardly through said bit body, a conically shaped recess in the bottom of said bit body, the apex of said conical recess lying substantially in the axis of rotation of said bit, a portion of said conical surface less than its circumference being cut away near the apex thereof to provide an open communication from said channel into said conically shaped recess the uncut-away portion of said conical surface being effective under the weight on the bit to continually break away the apex of the conical formation produced by said bit during progressive drilling thereby, a plurality of grooves cut in and extending from said open communication to the periphery of said bit, the sections of said conical surface intermediate said grooves carrying [heterogeneously mounted] diamond cutting elements at least one of said sections of said conical surface terminating substantially at the center of rotation of said bit, and at least one of said sections terminating short of the center of rotation of said bit.

2. A diamond drill bit for drilling in hard formations comprising a bit body, a generally conically shaped recess in the bottom of said bit body, a channel extending downwardly through said bit body and opening into said conical recess well above the base of said bit, a plurality of grooves cut in the conical surface of said conical recess extending from said channel to the periphery of said bit, the segmental sections intermediate said grooves carrying [heterogeneously mounted] diamond cutting elements, at least one of said segmental sections of said conical surface terminating substantially at the center of rotation of said bit, and at least one of said sections terminating short of the center of rotation of said bit.

3. A diamond drill bit for drilling in hard formations comprising a bit body, a generally -Y of grooves cut inthe conical surface of said I:

conical recess extending from said channel to the periphery of said bit and extending upwardly from the base of the said bit a substantial distance on the outer wall of the bit body, the segmental sections intermediate said grooves carrying [heterogeneously mounted] diamond cutting elements, at least one of said segmental sections of said conical surface terminating substantially at the center of rotation of said bit, and at least one of said sections terminating short of the center of rotation of said bit.

4. A diamond drill bit for drilling in hard formations comprising a bit body, a generally conically shaped recess in the bottom of said bit body, a channel extending downwardly through said bit body and opening into said conical recess well above the base of said bit, a plurality of grooves cut in the conical surface of said conical recess extending from said channel to the periphery of said bit, the cross sectional area of said channel being greater than the total cross sectional area of said grooves, the segmental sections intermediate said grooves carrying [heterogeneously mounted] diamond cutting elements, at least one of said segmental sections of said conical surface terminating substantially at the center of rotation of said bit, and at least one of said sections terminating short of tne center of rotation of said bit.

5. A diamond drill bit for drilling in hard formations comprising a bit body, a generally conically shaped recess in the bottom of said bit body, a channel extending downwardly through said bit body and opening into said conical recess Well above the base of said bit, a diamond holding matrix adhered to the generally conical surface of said conical recess and extending to the periphery of said bit, a plurality of circumferentially spaced grooves cut in said matrix extending from said channel to the periphery of said bit, the segmental sections of said conical surface intermediate said grooves carrying-[heterogeneously mounted] diamond cutting elements, at least one of said segmental sections of said conical surface terminating substantially at the center of rotation of said bit, and at least one of said sections terminating short of the center of rotation of said bit.

6. A diamond drill bit for drilling in hard formations comprising a bit body, a fluid conducting passageway extending downwardly through said bit body, a substantially conically shaped recess in the bottom of said bit body, the center of said conical recess lying substantially in the axis of rotation of said bit body, said fluid conducting passageway opening into said conical recess, a plurality of grooves cut in the wall of said conical recess and 'extending from said passageway to the periphery of said bit dividing the surface of said conical recess into a plurality of sections each of which carries [heterogeneously mounted] diamond cutting elements, at least one of said sections extending substantially to the axis of rotation of said bit body, said bit body embracing a removable and replaceable element, a portion of which is adapted to form a part of said section extending substantially to the axis of rotation of said bit body, and at least one of said sections terminating short of the center of rotation of said blt.

JOHN A. ZUBLIN.

REFERENCES CITED The following references are of record in the file of this patent or the original patent:

UNITED STATES PATENTS l Date 

